The present invention generally relates to pliers which may be operated by hand. Such pliers are actuated by hand by two handles of a drive being pivoted with respect to one another to attain an actuation stroke. One of the end points of the actuation stroke corresponds to the opened position of the pliers, and the other end point of the actuation stroke corresponds to the closed position of the pliers. With such pliers, work pieces are processed in some way, for example, electrical conductors are connected to end sleeves or strands by pressing, wires are cut or work pieces are deformed. The head of the pliers includes a corresponding appropriate tool which usually is formed by two associated working jaws or pressing jaws being located inside the frame of the pliers head. Usually, one of the jaws is stationary, whereas the other jaw is supported to be movable with respect to the first jaw inside the frame of the pliers head. There is a great number of pliers including respectively designed jaws depending on the desired use of the pliers.
Hand operable pliers are known from German Patent No. DE 34 11 397 C2. The known pliers include two main elements, namely a pliers head and a drive. Both elements are designed as plates. The pliers head includes a closed frame in which the stationary jaw is supported and in which the movable jaw is guided to be movable with respect to the stationary jaw. The movable jaw includes a protrusion being directed towards the drive, the protrusion ending in a circumferentially opened recess having the shape similar to a semicircle and contacting a pressure bolt of the drive at least during a part of the actuation stroke of the drive. The drive includes two handles being movable with respect to one another about a common joint. The common joint includes the pressure bolt at which the protrusion of the movable jaw is supported. In addition to the pliers head and to the drive, two pulling tongues are arranged as third elements. The ends of the pulling tongues facing the pliers head are connected to the frame of the pliers head by connecting joints, while their other ends are connected to the handles by joints. The four joints include detachable bolts in a way that the drive including the handles may be connected to different pliers heads by using the pulling tongues. In this way, different tools may be alternatively connected to the same drive. However, it is not easy to exchange or replace a pliers head. Certain skills are required, and it is necessary to understand the construction of the pliers. The four detachable bolts may not get lost during the exchange, and they may not be interchanged. To introduce the bolts, the respective elements have to be aligned in a respective position. This is not easy since the pulling tonguesxe2x80x94 even when they are connected to the frame of the pliers head after pushing the two bolts of the connecting joints inxe2x80x94 still are freely pivotable. Consequently, it is necessary to align the ends of the pulling tongues facing the drive with respect to the axes of the connecting joints at the side of the drive. This alignment is not possible in the closed position of the handles of the drive since the movable jaw is located in the opened position at the pliers head due to opening springs usually being located in the pliers head. On the other hand, there is the problem of the handles of the drive not having a defined opening position. Instead, in the dismounted position of the pliers head, they may be opened to an extent that the handles enclose an angle of approximately 180 degrees. The elements of the connecting joints cannot be positioned in a way that the bolt may be easily inserted.
Another trend of development in the art of controlling the majority of jaws without having to manufacture complete pliers is known from German Patent No. DE 40 23 337. A majority of dies is located at one jaw in a concentrated way. The jaw is arranged to be pivotable about an axis being located in a direction perpendicular to the plane of main extension of the frame in a way that the different dies being associated with different sizes may be alternatively used. The parts of the pliers are not designed to be detached from each other.
Furthermore, pliers including exchangeable jaws are known in the art. In this wayxe2x80x94 when the desired application changesxe2x80x94 only the respective jaw is exchanged. Special constructive precautions have to be met to guide and to support the respective jaw.
The present invention generally relates to pliers for processing work pieces. More particularly, the present invention relates to hand operable pliers including a pliers head and a drive. The pliers head includes a frame, a stationary jaw and a movable jaw, and it is designed and arranged to be replaceable. The drive includes two handles and a common joint being designed and arranged to connect the handles to be pivotable about the common joint and to allow for an opening movement and for a closing movement of the handles. The common joint forms a pressure bolt. The movable jaw is designed and arranged to be detachably supported at the pressure bolt. The drive further includes a plurality of connecting members each being designed and arranged to be detachable, two pulling elements being associated with the drive and each having a first end facing the pliers head and a second end facing the handles. The first end is designed and arranged to be rotatably connected to the pliers head by one of the connecting members to form a connecting joint. The second end is designed and arranged to be non-detachably and rotatably connected to one of the handles. The drive also includes a stop being designed and arranged to be limit the opening movement of the handles.
The present invention also relates to a pliers system including a plurality of pliers heads and plurality of drives which may be differently combined and interconnected to realize different types of pliers for different operations on work pieces, for example for crimping, connecting, pressing, cutting and so forth.
The novel pliers have a design which makes it easier to handle them. Different pliers heads may be easily and quickly coupled to different drives for actuating the pliers.
In the novel pliers, the pulling elements or pulling tongues are not used as a third element in addition to the pliers head and to the drive, but they are clearly associated with the drive. This means that during an exchange of the pliers head, the pulling elements remain located at the drive, and only two connecting joints have to be loosened or detached. Additionally, the opening stroke or opening movement of the handle of the drive is limited by a stop. The drive unit has a determined, reproducible position in its opened position. This opened position is located between the common joint of the handles acting as a pressure bolt and the two connecting joints of the pulling elements at the drive which may not be loosened. The axes of these three elements define a triangle which has a determined, defined relative position in the opened position. The pulling elements are pivotable about the connecting joints at the side of engagement, and they may not be loosened at this place. However, during this pivotal movement, the first ends facing the pliers head are guided on defined circular arcs such that the aligned position between the first ends of the pulling elements facing the pliers head and the frame of the respective pliers head is easy to be found to insert bolts or other detachable connecting members in the coupled position of the pliers. In this way, the exchangeable pliers head and the drive together form actuatable pliers. The alignment between the movable jaw of the respective pliers head and the pressure bolt of the common joint of the drive is automatically achieved without requiring special skills. The position of the jaw being movably guided in the pliers head is used. Usually, opening springs are located in each pliers head, the opening springs moving the movable jaw to reach and maintain a position corresponding to the limited opening position of each drive.
It is especially preferred if the first ends of the pulling elements of the drive facing the pliers head are coupled with one another at a determined distance by a connecting element or a yoke. The distance corresponds to the distance between the axes of the connecting joints. The inserted connecting element is an additional element being associated with the respective drive. Each drive includes at least one connecting element. In many cases, it includes two connecting elements in a symmetric arrangement with respect to the plane of main extension of the pliers. This plane is defined by the pliers head and by the drive. To alternately couple the drives and the pliers heads being part of an exchangeable pliers system, the connecting element determines one common distance between the axes of the connecting joints for the connection. The connecting element is permanently connected to the ends of the pulling elements facing the pliers head in a pivotal way such that a four point joint system is defined. In this way, when one axis of a connecting joint is positioned, the axis of the other connecting joint is also positioned as desired. As soon as one securing member has been inserted, the other securing member may also be easily inserted.
In an especially preferred embodiment of the novel pliers, the connecting element is linearly guided at the drive. The linear guidance of the connecting element is aligned in a direction towards the drive of the pliers head. In this way, the determined, fixed distance between the axes of the connecting joints is fixedly determined in space with respect to the pressure bolt of the common joint of the handles. The three connecting points or connecting locations have a definite, reproducible position with respect to one another in the opened position of the pliers such that the three respective connecting points of each pliers head being located in the same position with respect to one another may be arranged to overlap with one single movement. Consequently, exchanging the pliers head or the drive being connected to the pliers head is especially easy.
In an especially preferred constructive design of the novel pliers, the connecting element may be guided at the pressure bolt of the common joint of the handles of the drive. The pressure bolt forms the stop for a limited stroke at least in the opening direction. The pressure bolt forming the stop also limits the opening stroke of the handles and the relative position of the pressure bolt with respect to the connecting joints. The opened position of the drive, meaning the angle between the two handles of each drive being defined by the stop, is the exchanging position for the pliers head. The three connecting points being located at the drive, meaning the axes of the elements of the connection joints of the pulling elements facing the pliers head and the axes of the common pressure bolt of each drive are located at the same relative position and space as the axes of the respective connecting elements at each pliers head. These elements of the pliers head are also located in the opened position. This is caused by opening springs being located in the pliers head and a respective limitation of the stroke of the movable jaw in the pliers head.
Especially, the connecting element or the yoke may include an elongated hole through which the pressure bolt of the common joint of the two handles of the drive protrudes. Such an elongated hole at least at one of its ends should be designed to be circumferentially closed to form the limitation for the opened position of the handles of the drive. Its other end may also be designed to be closed to limit the closed position. In many cases, and especially in case when the closed position is designed to be adjustable, such a limitation is not required, or if it exists, it is located at a place at which it is not active.
There are a number of different possibilities of designing the pulling elements and/or the detachable connecting members. It is advantageous if the detachable connecting members are associated with the respective drive. As detachable connecting members, bolts which may be pulled out, screws including nuts or such not including nuts, guide pins and the like may be used. The pulling members may also have a variety of designs. It is especially advantageous if the ends of the pulling members facing the pliers head have a cranked design in a direction perpendicular to the plane of main extension of the pliers. Such a cranked design allows for the possibility of arranging the pliers head symmetrically with respect to the plane of main extension of the pliers. This is advantageous to uniformly transmit forces. Additionally, the cranked portions may form positioning stops to limit the insertion movement between the pliers head and the drive. This simplifies the insertion of the detachable connecting members. Especially, it is possible to design the ends of the pulling members facing the pliers head symmetrically with respect to the plane of main extension of the pliers to be cranked in a double way to form positioning supports for protrusions of the frame about the axes of the connecting joints. When the pliers head is exchanged, the pliers head to be newly inserted is guided with respect to the drive in two planes. Consequently, it reaches a limited insertion position in which the three connecting points with their axes are aligned such that the detachable connecting members may be inserted without additional centering efforts.
The detachable connecting members may be supported at the connecting element being associated with the drive to be movable in a direction perpendicular to the plane of main extension of the pliers to a limited extent. In this way, the detachable connecting members are captively connected and held at each drive. These connecting members are comparatively small elements which may easily get lost during assembly or disassembly of the pliers.
In a preferred embodiment of the novel pliers, the pulling members or connecting members, two connecting elements and the frame of the pliers head are designed and arranged to be substantially symmetric with respect to the plane of main extension. This arrangement allows for transmitting forces between the drive and the respective pliers head during use of the pliers in a good and safe way. The connecting members, especially insertion bolts, are not subjected to unbalanced bending forces. The two connecting elements or yokes may have identical designs.
In this way, a system of different hand operable pliers is achieved. The system includes a plurality of drives and a plurality of pliers heads which have a common determined mutual distance between the axes of the connecting joints and a common relative position of the pressure bolt with respect to the connecting joints. Usually, the number of pliers heads will be greater than the number of drives. It is especially preferred to use two drives only differing with respect to the lengths of the respective handles to change the forces which may be applied by hand at the respective pliers head in response to the necessary force demand.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and the detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims.